The aim of the proposed study is to continue to investigate thalamocortical and subcortical connections of monkey and cat brain by use of whole brain serial sections in gapless series following production of experimental lesions. Circumscribed subpial cortical lesions or stereotaxic radio frequency lesions of subcortical nuclei will be produced. Following adequate survival, demyelination, nerve cell loss and gliosis will be evaluated by use of Loyez and cresyl violet stains, supplemented where indicated by special techniques. The study will allow more accurate topographic relations to be determined than are usually possible in vescular or surgical lesions of human brains.